Vacuum packaging method and apparatus

Abstract

Vacuum packaging apparatus and method for evacuating and heat sealing bags employs a clamp, swingable over substantially the full length of the bagged product, to effect a temporary air-tight seal of an evacuated bag during transport of the evacuated bag from an evacuating zone to a heat sealing zone. The apparatus also includes a platen having a shallow V-shaped configuration to cradle the bagged product and the V-shaped being flattened to a plane and the platen being elevated to facilitate automatic removal of the bagged product from the platen.

Having described the invention in detail, what is claimed as new is: 
     
       1. Vacuum packaging apparatus comprising at least one carrier movable in a closed path through successive loading, evacuation, heat sealing and unloading zones, each carrier comprising: a) a platen for receiving an open bag containing an article to be packaged, said platen having opposite first and second ends;   b) an upstanding anvil adjacent said platen first end for receiving an open neck portion of said bag draped across said anvil;   c) a clamp having end portions journaled at either side of said platen such that said clamp spans said platen and is pivotable over said platen from and between a full open position wherein said clamp is disposed adjacent said platen second end and a full closed position wherein said clamp is disposed against said anvil;   d) drive means operable in an interval between said loading and evacuating zone for swinging said clamp from said full open position and towards said full closed position; and   e) latch means operable in said evacuation zone for engaging and drawing said clamp tightly against said anvil to effect a mechanical air tight seal of the bag neck draped across said anvil.   
     
     
       2. Apparatus as in claim 1 wherein said platen is supported on a base and said clamp comprises: a) a generally U-shaped member spanning said platen;   b) an arm at each side of said U-shaped member, each arm journaled at one end to said base and attached at an opposite end to said U-shaped member; and   c) said drive means engaging said arm at the journal of said arm to said base.   
     
     
       3. Apparatus as in claim 2 wherein the attachment of each arm to said U-shaped member provides for limited pivotal movement of said U-shaped member relative to said arm. 
     
     
       4. Apparatus as in claim 1 wherein each carrier includes: a) a base having spaced upright walls;   b) said platen being disposed between said walls; and   c) said anvil upstanding from said base and extending generally transverse said walls and being supported generally at the elevation of the top of said walls.   
     
     
       5. Apparatus as in claim 4 wherein each of said clamp end portions is journaled to one of said walls and said clamp spans the space between said walls. 
     
     
       6. Apparatus as in claim 4 wherein said platen is supported on elevating means for vertically moving said platen relative to said base from and between a low position adjacent said base and a high position above the level of said walls. 
     
     
       7. Apparatus as in claim 6 including drive means at said unloading station operably engageable with said elevating means for vertically moving said platen to said high position and a pusher at said unloading station for moving a bagged article from said elevated platform and over said one of said walls to discharge said bagged article from said carrier. 
     
     
       8. Apparatus as in claim 4 wherein each clamp end portion is an arm, each arm at one end being connected to said clamp and at an opposite end being journaled to one of said walls and including cooperating members on at least one of said arms and its associated wall for holding said clamp short of its full closed position to permit the evacuation of air through the portion of said bag draped across said anvil. 
     
     
       9. Apparatus as in claim 8 wherein said cooperating members comprise: a) a stop;   b) a spring biased member engageable against said stop just prior to said clamp reaching said full closed position and said spring biased member being compressed against said stop to permit the movement of said clamp to said full closed position upon operation of said latch means.   
     
     
       10. Apparatus as in claim 9 wherein said stop is on one of said walls and said spring biased plunger is carried by one of said arms journaled thereto. 
     
     
       11. Apparatus as in claim 2 including a latch member connected to and extending from each leg of said U-shaped member, said latch member being said engageable by said latch means for drawing said clamp tightly against said anvil. 
     
     
       12. Apparatus as in claim 11 wherein the centroid of said U-shaped member lies on an axis extending through the point of connection of each latch member to said U-shaped member. 
     
     
       13. Apparatus as in claim 1 wherein said platen is supported on a base and each carriage includes an elevating means for raising and lowering said platen relative to said base. 
     
     
       14. Apparatus as in claim 13 wherein said platen comprises: a) two sections hinged together along a midline and defining an included angle therebetween; and   b) means for changing said included angle as said platen is raised and lowered.   
     
     
       15. Apparatus as in claim 14 wherein said included angle is less than 180° when said platen is at a lowered position and is increased to about 180° when said platen is at an elevated position. 
     
     
       16. Apparatus as in claim 13 wherein said platen has a spine portion oriented along the midline of said carrier; a section hinged to said spine on either side of said midline; and said elevating means for raising and lowering said sections is a parallel motion linkage journaled at its ends to said base and spine. 
     
     
       17. Apparatus as in claim 13 including means at said unloading zone operable to engage and drive said elevating means for raising said platen to its highest elevation. 
     
     
       18. Apparatus as in claim 17 including means between said unloading and loading zones operably engageable with said elevating means for lowering said platen prior to the placement thereon of said bag containing an article to be packaged. 
     
     
       19. Vacuum packaging method comprising the steps of: a) moving a carrier through successive loading, evacuating, heat sealing and unloading zones;   b) placing an open article-containing bag having a pre-closed end onto said carrier at said loading zone and arranging the open end of the bag to a flat width;   c) during transit between said loading and evacuating zones, swinging a clamp member, which spans the article-containing bag over substantially the full length of the bag from a full open position adjacent the pre-closed end of the bag and towards a position adjacent to but spaced from the open end of the bag;   d) evacuating air from the article-containing bag in the evacuation zone and thereafter drawing said clamp member down to a position tightly clamped against the open bag end for effecting an air tight mechanical seal of the bag;   e) moving said carrier to said heat sealing zone and in transit exposing said article-containing bag to atmospheric pressure while maintaining said air tight mechanical seal;   f) heat sealing across the flat width of said bag to effect a permanent air tight seal thereof and then moving said carrier to said unloading zone;   g) releasing said clamp member and swinging it back over the length of the article-containing bag to the clamp full open position; and   h) removing the now sealed article-containing bag from the carrier at the unloading zone.   
     
     
       20. A method as in claim 19 wherein said carrier includes a base, spaced side walls upstanding from the base for supporting the clamp member, and a vertically moveable platen in the space between the walls defining a surface for receiving the article-containing bag, said method further comprising the steps of: a) moving said platen to a low level for receiving an open article-containing bag at said loading zone;   b) elevating said platen to an elevation above the level said walls at said unloading zone; and   c) pushing a sealed article-containing bag transversely from said elevated platen and over one of said walls to a stationary receiving platform.   
     
     
       21. A method as in claim 20 wherein said platen includes two hinged together portions defining an included angle therebetween of less than 180° and increasing said included angle when elevating said platen. 
     
     
       22. A method as in claim 21 comprising increasing said included angle to substantially 180° when elevating said platen. 
     
     
       23. A method as in claim 19 comprising the steps of: a) interposing bias means in the path of the clamp member to prevent it from reaching the tightly clamped position during said evacuating step and thereafter;   b) moving said clamp against the urging of said bias means to said tightly clamped position.   
     
     
       24. A method as in claim 19 wherein said clamp member is generally U-shaped and drawing said clamp member to a position tightly clamped against the open bag end comprises applying a force to the legs of said U-shape and directly said force through an axis which includes the centroid of said U-shaped member. 
     
     
       25. A method as in claim 19 including releasing said clamp member in said heat sealing zone. 
     
     
       26. A method as in claim 19 including swinging said clamp member back over the length of a sealed article-containing bag during transit of said carrier from said heat sealing zone to said unloading zone. 
     
     
       27. A method as in claim 19 wherein said carrier has a surface against which said heat sealing occurs and said heat sealing produces a heat sealed bag portion, further comprising releasing said heat sealed bag portion from said surface in said heat sealing zone. 
     
     
       28. A method as in claim 27 wherein releasing said heat sealed bag portion is accomplished by: a) releasing said clamp member in said heat sealing zone; and   b) moving the now heat sealed article containing bag relative to said surface.   
     
     
       29. A method as in claim 28 comprising elevating said now heat sealed article containing bag relative to said carrier to pull and strip the heat sealed portion from said surface.